Modern articles of footwear, such as athletic shoes, are a combination of many elements working together for the support and protection of the foot and the enhancement of athletic abilities. In general, an athletic shoe is divided into two parts: an upper and a sole. The upper is designed to snugly and comfortably enclose the foot. The sole is designed to attenuate ground reaction forces (i.e. imparts cushioning) and provide a broad, stable base to support the foot during ground contact. Typically, the sole structure of athletic footwear includes multiple layers, for example, a comfort-enhancing insole, a resilient midsole, and a ground-contacting outsole that provides both abrasion-resistance and traction. Additional traction, which may be attained by providing the outsole with cleat members, is desirable for certain sports, for example, football, baseball and soccer.
Cleat members have traditionally been molded with natural materials, such as rubber, or synthetic materials, such as high abrasion thermoplastic polyurethanes (“TPUs”). TPUs commonly used in such applications have a Shore A hardness of about 80 to 100, as measured by ASTM Method D-2240-91. Representative useful TPUs are sold by the Bayer Corporation under the trademarks TEXIN™ and DESMOPAN™. However, such cleat members tend to be either too soft and unstable or, if made of a suitable material and size so as to have sufficient strength and stability, they tend to be too heavy.
Cleat members may be formed of one-piece molded construction with the sole. Alternatively, cleat members may be removably secured to the sole, such as by a threaded member extending from the cleat member that is received by a threaded member in the sole.
It is an object of the present invention to provide a cleat member and an article of footwear including such a cleat member that reduces or overcomes some or all of the difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.